2/26/2008 @ 10:00AM

In Pictures: The World's 25 Dirtiest Cities

To see which cities in the world were dirtiest, we turned to Mercer Human Resource Consulting’s 2007 Health and Sanitation Rankings. As part of their 2007 Quality of Life Report, they ranked 215 cities worldwide based on levels of air pollution, waste management, water potability, hospital services, medical supplies and the presence of infectious disease. All cities are positioned against New York, the base city with an index score of 100. For the Health and Sanitation Rankings, the index scores range from the worst on the list–Baku, Azerbaijan, with a score of 27.6–to the best on the list–Calgary, Canada, with a score of 131.7.